Showing papers by "Central Tuber Crops Research Institute published in 2013"

Isolation of proline-based cyclic dipeptides from Bacillus sp. N strain associated with rhabitid entomopathogenic nematode and its antimicrobial properties

Abstract: Entomopathogenic nematodes (EPN) are well-known as biological control agents and are found to have associated bacteria which can produce a wide range of bioactive secondary metabolites. We report herewith isolation of six proline containing cyclic dipeptides cyclo(d-Pro-l-Leu), cyclo(l-Pro-l-Met), cyclo(d-Pro-l-Phe), cyclo(l-Pro-l-Phe), cyclo(l-Pro-l-Tyr) and cyclo(l-Pro-d-Tyr) from ethyl acetate extract of the Luria Broth (LB) cell free culture filtrate of Bacillus sp. strain N associated with a new EPN Rhabditis sp. from sweet potato weevil grubs collected from Central Tuber Crops Research Institute farm. Antimicrobial studies of these 2,5-diketopiperazines (DKPs) against both medicinally and agriculturally important bacterium and fungi showed potent inhibitory values in the range of μg/mL. Cyclic dipeptides showed significantly higher activity than the commercial fungicide bavistin against agriculturally important fungi, viz., Fusarium oxysporum, Rhizoctonia solani, and Pencillium expansum. The highest activity of 2 μg/mL by cyclo(l-Pro-l-Phe) was recorded against P. expansum, a plant pathogen responsible for causing post harvest decay of stored apples and oranges. To our knowledge, this is the first report on the isolation of these DKPs from Rhabditis EPN bacterial strain Bacillus sp.

Bioleaching of copper from pre and post thermally activated low grade chalcopyrite contained ball mill spillage

Abstract: Bioleaching of a low grade chalcopyrite (ball mill spillage material) was tested for copper recovery in shake flasks. The original samples (as received) were thermally activated (600°C, 30 min) to notice the change in physico-chemical and mineralogical characteristics of the host rock and subsequently its effect on copper recovery. A mixed culture of acidophilic chemolithotrophic bacterial consortium predominantly entailing Acidithiobacillus ferrooxidans strain was used for bioleaching studies and optimization of process parameters of both original and thermally activated samples. Mineralogical characterization studies indicated the presence of chalcopyrite, pyrite in the silicate matrix of the granitic rock. Field emission scanning electron microscopy coupled with Energy dispersive spectroscopy (FESEM-EDS) and X-ray Fluorescence (XRF) analysis indicated mostly SiO2. With pH 2, pulp density 10% w/v, inoculum 10% v/v, temperature 30°C, 150 r·min−1, 49% copper could be recovered in 30 days from the finest particle size (−1 + 0.75 mm) of the original spillage sample. Under similar conditions 95% copper could be recovered from the thermally activated sample with the same size fraction in 10 days. The study revealed that thermal activation leads to volume expansion in the rock with the development of cracks, micro and macro pores on its surface, thereby enabling bacterial solution to penetrate more easily into the body, facilitating enhanced copper dissolution.

Genetic diversity of Phytophthora colocasiae isolates in India based on AFLP analysis

Abstract: Phytophthora colocasiae that causes taro leaf blight is one of the most devastating diseases of taro which is widely distributed in India. Inter and intra-specific genetic diversity among P. colocasiae isolates collected from same field was assessed using amplified fragment length polymorphism (AFLP) marker. Seven primer pairs produced 431 markers, of which 428 (99.2 %) were polymorphic. Considerable genetic variability was displayed by the isolates. The average value of the number of observed alleles, the number of effective alleles, mean Nei’s genetic diversity, and Shannon’s information index were 1.993, 1.385, 0.261, and 0.420, respectively. Analysis of molecular variance (AMOVA) showed that the majority (85 %) of the diversity were present within populations of P. colocasiae. Dendrogram based on AFLP molecular data using the unweighted pair group method with arithmetic mean (UPGMA) classified the P. colocasiae isolates into two major clusters irrespective of their geographical origin. Clustering was further supported by principle coordinate analysis. Cophenetic correlation coefficient between dendrogram and original similarity matrix was significant (r = 0.816). The results of this study displayed a high level of genetic variation among the isolates irrespective of the geographical origin. The possible mechanisms and implications of this genetic variation are discussed.

Molecular Studies on the Transmission of Indian Cassava Mosaic Virus (ICMV) and Sri Lankan Cassava Mosaic Virus (SLCMV) in Cassava by Bemisia tabaci and Cloning of ICMV and SLCMV Replicase Gene from Cassava.

Abstract: Cassava mosaic disease, caused by cassava mosaic geminiviruses are transmitted by Bemisia tabaci. The B. tabaci adults from colonies reared on virus free cassava plant produced from apical meristem culture was studied to determine their ability to transmit Indian cassava mosaic virus (ICMV) and Sri Lankan cassava mosaic virus (SLCMV) from cassava to cassava. Virus free plants were confirmed by polymerase chain reaction (PCR) using geminivirus degenerate primers. The virus acquisition access period (AAP) of 48 h on virus infected cassava leaves and 48 h virus inoculation access periods on virus free healthy leaves were investigated. Both ICMV and SLCMV were absolutely transmitted by whiteflies reared on cassava. Virus specific primers were designed in the replicase region and used to detect virus in B. tabaci after different AAP. The PCR amplified replicase genes from virus transmitted cassava leaves were cloned the plasmid DNA was isolated from a recombinant colony of E. coli DH5α after their confirmation by colony PCR and sequenced them. The nucleotide sequences obtained from automated DNA sequencing were confirmed as ICMV and SLCMV replicase gene after homology searching by BLAST and found to be a new isolates. The nucleotide sequences of new isolates were submitted in GenBank (accession number JN652126 and JN595785).

Mathematical modeling and thin-layer drying kinetics of bamboo slices on convective tray drying at varying temperature

Abstract: This study investigated the thin-layer drying characteristics of bamboo slices in a convective tray dryer with three different temperatures viz., 55, 65 and 75C and fit the experimental data to four drying models to identify the best fit model and drying temperature. The drying rate curves of slices typically demonstrate a smooth diffusion controlled drying behavior. The drying rate at the beginning of the process was generally lower at 55C, with a marked difference between it and the other temperatures. The difference between MRs increased gradually at the commencement of drying and the time required for reaching equilibrium moisture content decreases with increasing temperature. The average value of coefficient of determination (r2) and RMSE revealed values varied between 0.94–0.99 and 0.014–0.073, respectively. Page and logarithmic models obtained the highest r2 and least RMSE at all temperatures and better reflected the drying mechanism of bamboo slices than exponential model. Rehydration ratio elevated when salt solution used for rehydration and the weight gain was more irrespective of temperature. Superior rehydration was noticed when the slices were dried at 65C, and it was relatively poor at 75C and 55C. Products dried at 65C recorded highest scores for visual appearance and colour at the end of drying. PRACTICAL APPLICATIONS Consumers are inclining towards taking health-promoting products from nontraditional sources. Bamboo shoots are now an important food crop in the international food market. Bamboo shoot being low in fat, high in dietary fiber and rich in mineral content, like an ideal vegetable, has been used traditionally the world over. The market for bamboo shoots is growing steadily, and more and more people are developing a taste for them. Processing while keeping nutrients intact and enhancement of shelf life of the value-added products assume great significance for business potential due to seasonal availability of bamboo shoots. It would demand process standardization for small-scale processing units. Therefore, the use of hot air in controlled cabinet drying through convective air is far more rapid and provides uniformity and hygiene for industrial food drying processes. Therefore, this study deals in detail about dynamics of thin-layer drying kinetics of bamboo slices and its quality evaluation by rehydration and sensory process.

Starch-g-Copolymers: Synthesis, Properties and Applications

Abstract: Starch is one of the cheapest and most abundant natural carbohydrate biopolymers and is compatible with hydrocolloids and other water-soluble polymers. Therefore, it can be an effective component in multifunctional systems. To impart end use specific properties, starch is often modified. Chemical modification of starch by grafting various monomers onto it has been found attractive to impart desirable properties to starch without sacrificing its biological nature. Graft copolymerisation is one way to introduce biodegradability and improved properties to a polymer. Usually graft copolymerisation reactions are carried out by free radical initiated polymerisation reaction and in the literature different types of initiating systems are reported. Depending upon the type of monomers and the conditions employed the properties of the starch-graft-copolymers vary to a large extent. In this chapter, the various techniques used for the synthesis of starch-graft-copolymers, their properties and possible end uses are discussed in detail.

Gender Roles in Agriculture: The Case of Afghanistan

Abstract: Technological interventions aiming to improve livelihoods that bring gender equity can become successful only when the prevailing gender roles in society and access to different livelihood opportunities are fully understood. This article analyses gender roles in agriculture in the conservative patriarchal society of Afghanistan. Rapid appraisal was conducted through focus group interviews, participatory resource mapping, and so on, in seven villages each from Nangarhar and Baghlan provinces of Afghanistan. Educated women coordinators, facilitators and activists and well established womens’ groups were used to reach and target key women informants as they are not allowed to interact directly with male researchers. Their participation was more in livestock related activities. The study indicated that women’s involvement was less than men’s in both livestock and crop related activities. Age, social stigmas, poverty and shortage of labour influence the gender division of labour, decision-making ability and pa...

Sustained release enteric coated tablets of pantoprazole: formulation, in vitro and in vivo evaluation.

Abstract: In this study, an attempt was made to deliver pantoprazole in a sustained manner using delayed release tablets. The tablets were prepared by the wet granulation method using HPMC, cassava starch and polyvinyl pyrrolidine as polymers, Avicel PH 102 (MCC) as filler and potato starch as binder. The prepared tablets were evaluated for hardness, mass variation, friability and drug content uniformity, and the results were found to comply with official standards. The prepared tablets were coated using an enteric coating polymer such as cellulose acetate phthalate, Eudragit L100 and drug coat L100 by the dip coating method. The in vitro release was studied using pH 1.2 acidic buffer and pH 6.8 phosphate buffer and the study revealed that the prepared tablets were able to sustain drug release into the intestine. The anti-ulcer activity was evaluated by a water immersion stress induced ulcer model. The enteric coated pantoprazole tablets significantly reduced ulcer formation.

Meiosis and sexual fertility of autotetraploid clones of greater yam Dioscorea alata L.

Abstract: Meiosis in the tetraploid (2n = 80) males of Dioscorea alata L. was investigated for the first time. During metaphase I, the chromosomes were associated mostly in 6–8 quadrivalents and the remaining ones as bivalents with no trivalents or univalents. Anaphase I and subsequent stages of meiosis were normal. The observation of quadrivalents in the tetraploids provides cytological evidence for autotetraploidy. The autotetraploid males and females were highly fertile and they produced viable seeds on artificial pollination. Pollination between diploids (2n = 40) and tetraploids (2n = 80) were also successful via embryo rescue, producing triploid (2n = 60) progenies. The discovery of fertile autotetraploids could initiate polyploidy breeding in D. alata by conventional hybridization for the first time. The reduced number of quadrivalents and the high fertility of the autotetraploids are thought to be the result of partial diploidization of meiosis. The findings also refute the assumption of the allopolyploid origin of D. alata from two putative progenitors.

Cassava starch–konjac glucomannan biodegradable blend films: In vitro study as a matrix for controlled drug delivery

Abstract: Cassava starch (ST)–konjac glucomannan (KGM) blend films were prepared, characterized, and their suitability as matrices for the sustained release of a model drug, theophylline (Thp) was investigated. Structural studies showed that there was a good compatibility between ST and KGM and also revealed the existence of strong interaction between Thp and the polymer blend. The thermal stability of the films did not alter on blending of the two polymers. The water vapor transmission rate (WVTR) and swelling capacity of the blend films were higher than that of the neat ST, while lower than that of the neat KGM films. The drug release was related to the pH of the medium and the relative humidity (RH) under which the films were stored. The drug release data fitted well to Higuchi kinetic model and the mechanism corresponds to anomalous transport with non-Fickian kinetics corresponding to coupled diffusion/polymer relaxation. The rate of drug release was significantly (p<0.05) and positively correlated with the degree of erosion of the blend films. The study showed that the blend film with a composition, ST: 1.5 × 10−3 kg and KGM: 1.5 × 10−3 kg with 20% glycerol as plasticizer stored at a relative humidity in the range 11–53% was appropriate for the sustained release of the less water soluble drug, theophylline.

Molecular evidence supports hypervariability in Phytophthora colocasiae associated with leaf blight of taro

Abstract: The oomycete Phytophthora colocasiae that causes taro leaf blight is the most devastating disease of taro and is widely distributed worldwide. Molecular and phenotypic techniques were employed for assessing and exploiting the genetic variability among four populations of P. colocasiae obtained from a fine spatial scale (multiple leaf blight lesions on single taro leaf). Phenotypic characters such as virulence, morphology and mating type showed no variation. ITS characterization revealed detectable polymorphism among isolates of P. colocasiae. The mean number of haplotypes (H), haplotype diversity (HD), nucleotide diversity (π), and nucleotide substitution rate (θ) among analyzed sequences were 6.75, 1.00, 0.069, and 0.088 respectively. High levels of inter and intra specific variation were detected by random amplified polymorphic DNA (RAPD) assays. Moderate genetic diversity (H = 0.2651) was observed among populations of P. colocasiae. Analysis of molecular variance (AMOVA) confirmed that most of the genetic variability was confined to within a population (63.54 %). The coefficient of genetic differentiation among populations (G ST ) was 0.2007 and estimates of gene flow (Nm) among populations was 1.991 migrants per generation. Cluster analysis using UPGMA revealed that individuals from the same population failed to cluster in one distinct group. The results of the study reveal considerable genetic diversity among and within populations of P. colocasiae obtained from fine spatial scale. The possible mechanisms and implications of this genetic variation are discussed.

Crop and water productivity, profitability and energy consumption pattern of a maize-based crop sequence in the North Eastern Himalayan Region, India

Abstract: Mono-cropping is the most common farming practice followed in the North Eastern Hilly Region (NEHR) of India and farmers leave the land fallow after harvesting the main crop. The identification of suitable sequential crops is essential to increase the cropping intensity, land-use efficiency and overall productivity of the land. Therefore, a study was carried out during 2008–09, 2009–10 and 2010–11 on maize (rainy season) followed by table pea, mustard, French bean and groundnut (post rainy season). Sequence crops were imposed with paddy straw mulch at 5.0 t ha−1 and without mulch. The availability of water and moisture retention was higher (p < 0.05) on mulched plots, yield was also higher. However, recorded soil temperature was higher on mulched plots at 08.00 hours and lower at 12.00 and 16.00 hours compared with the no-mulch plots. Recorded maize equivalent yield, production efficiency, economics and total energy use and output (MJ ha−1) were higher for maize–French bean.

Optimization of media and temperature for enhanced antimicrobial production by bacteria associated with Rhabditis sp.

Abstract: Background and Objectives: Entomopathogenic nematodes, belonging to the family heterorhabditis and steinernematidae, are reported to be symbiotically associated with specific bacteria and the secondary metabolites produced by these bacteria possess antimicrobial activity. In this study, bacteria were isolated from nematodes belonging to the family rhabditidae, and the antimicrobial activity was tested against four bacteria viz. Bacillus subtilis MTCC 2756, Staphylococcus aureus MTCC 902, Escherichia coli MTCC 2622, and Pseudomonas aeruginosa MTCC 2642 and five fungi viz. Aspergillus flavus MTCC 183, Candida albicans MTCC 277, Fusarium oxysporum MTCC 284, Rhizoctonia solani MTCC 4634 and Penicillium expansum MTCC 2006. Materials and Methods: The isolated bacteria were cultured in nutrient broth (NB), Luria broth (LB) and Tryptic soya broth (TSB) at 25, 30 and 35oC. Cell free culture filtrate was prepared by centrifugation and was separated into organic and aqueous fractions. Organic fraction was concentrated and tested for antimicrobial activity. Results: The culture filtrate of the bacteria isolated from the entomopathogenic Rhabditis sp. was found to possess antimicrobial activity against the four bacteria and five fungi tested. The bacterium grew well in TSB, LB and NB media though in TSB yield and activity were higher. Antimicrobial activity was higher at 30oC as compared with 25 or 35oC. HPLC analysis indicated major differences in peak areas and retention times at different temperatures. Increased number of peaks with higher peak areas was obtained at 30oC. Conclusion: The study suggests that the bacteria could produce more bioactive molecules effective against medically and agriculturally important bacteria and fungi depending on culture media and temperature. Modified media could yield different types of molecules effective against diseases/disorders of plant, animals and humans.

Computer simulation of cassava growth: a tool for realizing the potential yield

Abstract: In this article, a process model (SIMCAS) for simulating the growth of cassava is proposed. Crop phenology was simulated as a function of growing degree days (GDD). New algorithms are used in this model to simulate different components of crop phenology. Branching is simulated as a function of the number of leaves and total dry matter produced. Standard methods were followed to compute solar radiation and photosynthesis. Sensitivity analysis confirmed the importance of canopy size on tuber yield. Algorithms for estimating stress due to a shortage of water, nitrogen and potassium are also included in this model. An attempt was made to predict the final yield under field conditions by multiplying stress values by potential yield. The model was tested under different environments. The tuber yield predicted by this model is in good agreement with the corresponding observed values in most of the cases. Estimation of stress due to a shortage of nitrogen, potassium and water is the key aspect of this model. This...

Evaluation of fungicides on Indian isolates of Phytophthora colocasiae causing leaf blight of taro

Abstract: Leaf blight caused by Phytophthora colocasiae is the most destructive disease affecting taro (Colocasia esculenta) worldwide including India. Fungicides (primarily metalaxyl) remain as an important strategy to manage taro leaf blight in India over decades. It is important to monitor isolate sensitivity to identify build-up of fungicide resistance and thereby modify fungicide usage strategies. P. colocasiae isolates representing four different geographical regions of India were evaluated for their sensitivity to metalaxyl and three other commercially available fungicides viz. Samarth, Biofight and Akoton by poisoned media technique. All the isolates tested were sensitive to metalaxyl, nevertheless there is an increase in the effective concentration compared to the previous reports. Among the other fungicides, Samarth was found to be superior in completely inhibiting mycelial growth at 0.05% followed by Biofight at 1%. Metalaxyl and Akoton® shared a common inhibitory concentration at 2%. The most effective ...

Identification of true hybrid progenies in cassava using simple sequence repeat (ssr) markers

Abstract: For the maping of Cassava mosaic disease (CMD) resistance gene, CO2 and MNga-1 parents were used for hybridization to develop F 1 hybrid seeds and 153 progenies were planted in the field for genotyping. Out of the 75 SSR primers used for parental polymorphism, 57 produced polymorphic bands between parents and these were used to screen the 153 progenies of the cross for genotyping. Out of these 57 SSR primer pairs SSRY32, SSRY36, SSRY83, SSRY339, NS149 and NS890 loci produced single marker which clearly distinguished the parents. Based on the said six primers, 12 progenies out of 153 were identified as self pollinated seeds of CO2 female parent. So these types of SSR markers were very much useful for identification of true hybrid seedlings in the early stage of growth and genotyping of the progenies more accurately for gene mapping. DOI: http://dx.doi.org/10.3329/bjb.v42i1.15906 Bangladesh J. Bot. 42 (1): 155-159, 2013 (June)

Genetic Diversity Analysis in Taro Using Molecular Markers – An Overview

Abstract: Taro ( Colocasia esculenta L. (Schott.)) is an important root crop especially in the humid tropics and sub-tropics. It is one of the few crops that can adapt well to different agro-climatic conditions. Taro is thought to have been originated in the Indo-Malayan region probably in North Eastern India and Bangladesh. However, some studies suggest that there exists a parallel Pacific gene pool for taro, quite distinct from the Asian one. Due to the vegetative nature of the crop and as a result of fixing of somatic mutations, morphotypes are quite distinct even when they share the same genetic material. Hence, for breeding purposes, selection of the most divergent parents becomes difficult if one goes by morphological characterization alone. It is in this regard that molecular characterization attains its relevance. Here, the actual genetic diversity exhibited by the crop can be measured and utilized for breeding and conservation of genetic resources. Though a good amount of molecular work has been carried out in the Pacific and South-east Asian genepools, no systematic work has been undertaken in Indian taro germplasm collections, except for a few scattered reports. In this review, an attempt has been made to document thoroughly the major molecular markers used for the analysis of genetic diversity in taro and its application in the management of genetic resources.

Development of a triplex (YYYy) parental potato line with extreme resistance to potato virus Y using marker assisted selection

Abstract: SummaryThe present study was undertaken to validate a sequence characterised amplified region (SCAR) marker tightlylinked to the potato virus Y (PVY) resistant gene (Ryadg) and its further use to develop a triplex parental line using marker assisted selection (MAS). The expected SCAR marker was detected in 11 PVY-resistant genotypes, including putative duplex clones, and was absent in PVY-susceptible genotypes. The resistant genotypes were also screened by double-anitbody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) and the results agreed with the SCAR marker data. Based on having a high marker band intensity, three putative duplex clones (YY-3, YY-6, and YY-13) were selected and were inter-crossed to ascertain their duplex status. Based on the PVY resistant (R): PVY susceptible (S) segregation ratio of their three respective progenies, the three clones were confirmed to be duplex clones. Similarly, five putative triplex clones were selected from the segregating progenies of two diploid clones b...

In vitro synergistic activity of diketopiperazines alone and in combination with amphotericin B or clotrimazole against Candida albicans

Abstract: The synergistic anticandidal activity of three diketopiperazines [cyclo-(l-Pro-l-Leu) (1), cyclo-(d-Pro-l-Leu) (2), and cyclo-(d-Pro-l-Tyr) (3)] purified from a Bacillus sp. N strain associated with entomopathogenic nematode Rhabditis (Oscheius) in combination with amphotericin B and clotrimazole was investigated using the macrodilution method. The minimum inhibitory concentration and minimum fungicidal concentration of the diketopiperazines was compared with that of the standard antibiotics. The synergistic anticandidal activities of diketopiperazines with amphotericin B or clotrimazole were assessed using the checkerboard and time-kill methods. The results of the present study showed that the combined effects of diketopiperazines with amphotericin B or clotrimazole predominantly recorded synergistic (<0.5). Time-kill study showed that the growth of the Candida was completely attenuated after 12–24 h of treatment with 50:50 ratios of diketopiperazines and antibiotics. These results suggest that diketopiperazines combined with antibiotics may be microbiologically beneficial and not antagonistic. These findings have potential implications in delaying the development of resistance as the anticandidal effect is achieved with lower concentrations of both drugs (diketopiperazines and antibiotics). The cytotoxicity of diketopiperazines was also tested against two normal human cell lines (L231 lung epithelial and FS normal fibroblast) and no cytotoxicity was recorded for diketopiperazines up to 200 μg/mL. The in vitro synergistic activity of diketopiperazines with antibiotics against Candida albicans is reported here for the first time.

Effect of biocontrol agents and biofertilizers on root rot, yield, harvest index and nutrient uptake of cassava (Manihot esculanta Crantz)

Abstract: Cassava is an important subsidiary food and industrial raw material in the tropics. Root rot disease, caused by Phytophthora palmivora, poses a serious threat to cassava cultivation in Tamil Nadu, India. Field experiments (2008–09) were conducted to study the effect of biocontrol agents (Trichoderma spp. and Pseudomonas fluorescens) and biofertilizers (Azospirillum, vesicular–arbuscular mycorrhizal fungi and phosphorus-solubilizing bacteria) on root rot, yield, harvest index and nutrient uptake of cassava at two NPK rates. The design of the experiment was a split plot with two NPK rates, recommended and 50% recommended rate, as the main plot treatments and five biocontrol agents and biofertilizers as subplot treatments. The results clearly indicated that use of a bioinoculants consortium significantly reduced root rot infection/disease incidence over uninoculated controls. Azospirillum significantly improved the yield of cassava at 50% of the recommended rate of NPK. NPK rates had no significant impact on...

Complete Genome Sequence of Potato leafroll virus Isolates Infecting Potato in the Different Geographical Areas of India Shows Low Level Genetic Diversity.

Abstract: Five Potato leafroll virus (PLRV) isolates were collected from five states representing different potato growing parts of India. The ssRNA genome sequences of these isolates were determined. The genome comprised of 5,883 nucleotides and deduced genome organization resembled other PLRV isolates. About 97.6–98.7 % similarities was observed within the Indian isolates and were more close to European, Canadian, African, American and Czech isolates (95.8–98.6 %) than to an Australian isolate (92.9–93.4 %). These isolates were 43.7–53.1 % similar to other poleroviruses and 29.1–29.3 % to Barley yellow dwarf virus, a luteovirus. Out of five isolates, the isolate PBI-6 was recombinant one as detected by RDP3 software. Multiple sequence alignment of nucleotide and amino acid sequences of different ORFs indicated that the ORF 3 and ORF 4, corresponding to coat protein and movement proteins are more conserved than other ORFs. Amino acid changes specific to Indian isolates were observed and it was more in ORF 2 than in ORF 0, ORF 3 and ORF 4. This is the first report of complete genome sequence of PLRV isolates from India, which reveals low level genetic diversity.

Soil Fertility Management Strategies in Edible Yams and Aroids: A Review

Abstract: Soil fertility as well as nutrient management of crops depends on the different processes of nutrient dynamics viz., nutrient flow/movement, nutrient transformation, nutrient utilization and its absorption, which in turn influences not only the crop yield but also the quality of the produce. The interaction among the nutrients leading to these processes usually takes place in the soil, rhizosphere and also in the soil-plant system. Any disruption in these processes will result in the manifestation of various nutritional disorders. These processes at the different sites are affected by native soil characteristics and other extraneous factors. In this review, a thorough documentation of the different processes leading to nutrient dynamics in three species of edible yams viz., greater yam ( Dioscorea alata ), white yam ( Dioscorea rotundata ) and lesser yam ( Dioscorea esculenta ) and edible aroids viz., elephant foot yam ( Amorphophallus paeoniifolius ), taro ( Colocasia esculenta ) and tannia ( Xanthosoma sagittifolium ), including the response of independent nutrients as well as combination of nutrients on yield and quality, index leaf tissues, critical concentration of nutrients for deficiency/sufficiency and the nutritional disorders have been done.

Assessment of Genetic Diversity in Taro Using Morphometrics

Abstract: Taro is an important tropical tuber crop, used as a staple food or subsistence food by millions of people in the developing countries. A program was done to analyze and identify the same promising 20 selected local and Indian accessions taro, aiming at the characterization of the extent and distribution of genetic diversity using morphological marker with the define objectives ‘to find genetic variability amongst the 20 taro genotypes collected from different agro-climatic zones in India, in respect of plant physical (like length of main sucker, no of petioles, length of leaf lamina, wt. of side tuber, number of side tuber, estimated Corm yield, breadth of leaf lamina)’. The present study revealed that the genetic diversity recorded through physical parameters corresponded with the genetic diversity revealed through molecular data analysis. On the basis of D2 statistics the 20 genotypes were grouped into six different clusters (I-VI). Most of the local taro genotypes collected from different locations (BCC-1, BCC-2, BCC10, BCC15, BCC18, BCC-21, BCC24 and BCC-25) were placed in Cluster II with moderate intra cluster distance indicating their closeness, and showed similar phenotypic characters. The genotypes viz. FC-4, FC-11 and PKS1 were found to distantly relate to other genotypes and were grouped into Cluster III.

Selected Soil Enzyme Activities, Soil Microbial Biomass Carbon, and Root Yield as Influenced by Organic Production Systems in Sweet Potato

Abstract: A field experiment was conducted on Typic Rhedustalfs to determine the effects of various organic production systems. Results revealed that the soil microbial biomass carbon (SMBC) content was greatest with the application of 100% N through farmyard manure. The ratio index value of biofertilizer along with 50% N through any one of the organic sources were greater than 100% N through green leaf manure / vermicompost, integrated use of manure and fertilizer (conventional production system), and control (traditional system of production). Soil enzymes varied with the production systems. The urease, phosphatase, and β-glucosidase activities were more with greater nitrogen, phosphorus, and organic-matter treatments, respectively. The SMBC, soil enzymes, and microbial activity were very responsive to organic production systems, but their levels and activities were not reflected in sweet potato root yield.

Effect of light intensity on photosynthesis and accumulation of sennosides in plant parts of senna (Cassia angustifolia Vahl.)

Abstract: The production of secondary metabolites in medicinal plants is influenced by quality of light. Two senna cultivars (ALFT 2 and Sona) were studied under field conditions at four different light levels (25, 50, 70 and 100 % of full sunlight) for photosynthetic performance and sennoside accumulation. The cultivar ALFT 2 recorded highest P n values of 31.27 μmol CO2 m−2 s−1 at 100 days after sowing (DAS), whereas Sona recorded the highest value of 30.7 μmol CO2 m−2 s−1 at 60 DAS under 100 % light. Lowest P n values of 12.1 and 11.07 μmol CO2 m−2 s−1 were recorded in ALFT 2 (120 DAS) and Sona (150 DAS), respectively under 25 % light. Sennoside A reduced by 30 % under 25 % light in leaf tissue of ALFT 2, whereas, a reduction of only 16 % was observed in Sona. Highest sennoside B content was observed in ALFT 2 under full sun light (2.03 %). ALFT 2 recorded comparatively higher total sennosides (4.76 %) in pods than Sona (4.57 %) under full light. The gradual decline in P n with later growth stages could be the reason for steady decline in sennosides content, particularly in the leaves and pods of both the cultivars.

An Efficient Blade Type Rasper for Cassava Starch Extraction

Abstract: The cassava tubers, being highly perishable, should be immediately processed into starch or flour for value addition, which enhances the income of farmers resulting in food security and rural employment. Starch is generally prepared by wet extraction process, in which rasping or crushing is an important unit operation for the disintegration of the cell wall and washing out of the starch granules by water. In the commonly used raspers, mild steel sheets with nail punched protrusions are fixed around a wooden drum which rotates inside a crushing chamber to crush the tubers. The loss of sharpness of the protruded sheets necessitated frequent replacement and this increased the cost of processing. Hence a cost effective cassava rasper consisting of a crushing drum of mild steel pipe with high speed blade sets fixed on its circumference was developed and tested for its performance by changing the rasper speed and water inflow rate. Experiments were carried out to extract starch from cassava at different rasper speeds (1000, 1200 and 1400 rpm) and water inflow rates (7, 15 and 23 l min -1 ). The particle size analysis of the crushed mash obtained from the slurry showed that the volume surface mean diameter was found to be the highest followed by mass mean diameter and volume mean diameter. As the speed of rotation increased, the average particle size decreased, whereas with increase in water flow rate, the particle size increased. Maximum fineness modulus of the crushed mash was 4.82. The capacity of the machine was found to be about 900-1000 kg h -1 . The amount of starch extracted was 18.98% giving rise to a starch recovery of 83.39%.

Antioxidant and anticancer activity of 3,5-dihydroxy-4-isopropylstilbene produced by Bacillus sp. N strain isolated from entomopathogenic nematode

Abstract: 3,5-Dihydroxy-4-isopropylstilbene is a natural phytoalexin and was first identified as bacterial secondary metabolites. The aim of this study is to investigate in vitro antioxidant and anticancer activity of 3,5-dihydroxy-4-isopropystilbene purified from the cell free culture filtrate of Bacillus sp. N strain associated with rhabditid entomopathogenic nematode. Antioxidant activity was evaluated by five separate methods: free radical scavenging, reducing power assay, chelating effects on ferrous ions, NBT superoxide radical scavenging assay and hydroxyl radical scavenging activity. The stilbene recorded powerful antioxidant activity at various antioxidant systems in vitro. The superoxide radical scavenging (92.1 %) and hydroxyl radical scavenging (83.4 %) activities of the stilbenes at 100 μg/ml were higher than the butylated hydroxyanisole, the known antioxidant agent. Anticancer activity of stilbene was tested against breast cancer (MDAM B-231), cervical cancer (HeLa), lung cancer (A 549), colon cancer (HTL 116) cell lines using MTT method. The induction of apoptosis was studied by morphological analysis, apoptotic cell staining, caspase 3 activation assay and cell cycle analysis using flow cytometry. Stilbene induced significant morphological changes and DNA fragmentation associated with apoptosis in HeLa cells. Acridine orange/ethidium bromide stained cells indicated apoptosis induction by stilbene. Up-regulation of caspase 3 activity was also found in cells treated with stilbene. Flow cytometry analysis showed an increase in the percentage of apoptotic cells in sub G0 phase (2.4 % in control plates to 11.4 % in 25 μg/ml of stilbene) confirming the stilbene induced apoptosis. The results of the present study showed that stilbene demonstrated a strong antioxidant and anticancer effects. These suggest that stilbene may be used as possible natural antioxidant and anticancer agents to control various human diseases.